If this works correctly, you will have a desktop image that smoothly changes from normal.pct to warn.pct when your load average stays over 1.7 for five minutes or so. In my case, warn.pct is solid red, and heightened CPU usage for an extended period of time shows up as a slow background fade to fire engine red. If you are comfortable with perl, you can modify the if() statement to change images based on other chosen conditions, or show different images depending on situations that demand your attention.

In the discussion thread, a few people rightly point out that CPU monitors are a dime
a dozen, and can be placed on the desktop, dock, or anywhere else you like. The broader
point was that Mac OS X provides an easy entry into ambient visual displays, and the background
can be used to show whatever information you like - unread RSS feeds, instant messages,
to-do list backup, wind speed in Chicago.

An excellent example of this is Dunstan Orchard's site,
where the whole masthead is a visual indicator of the weather near his parents' home.

Andrew Baio notices
the similarity to Ambient Devices,
physical manifestations of the same idea. I'm not sure that I'd be willing to pay $150 to get
my stock market information as a subtly shifting color (WTF is it with stocks as the
standard pretext for any interesting information-related investigation?), and there's a
powerful tradeoff involved in choosing one specific piece of data for your ambient display.
On the other hand, I'm constantly amazed at my girlfriend's intuition for plant health (she
is a gardener). When you're looking for signs of disease or parasites, what is a plant but
an subtle gestalt of color, texture, and smell indicating some complex internal state?